This invention relates to barrier films for copper interconnects, and specifically to a method of enhancing coverage of titanium-based barrier metals.
There are three known precursors used in the metal-oxide chemical vapor deposition (MOCVD) of TiN or TiSiN films: tetrakis (dimethylamino) titanium (TDMAT) for TiN/TiSiN thin barrier films, tetrakis (diethylamino) titanium (TDEAT) for TiN/TiSiN films, and tetrakis (methylethylamino) titanium (TMEAT) used for barrier applications. Among those three, TMEAT offers the best process control and also provides better film properties, such as superior step coverage and lower resistivity.
T. Harada, et. al., in their paper Surface Modification of MOCVD-TiN Films by Plasma Treatment and SiH4 Exposure for Cut Interconnects, Conf. Proceedings ULSI XIV 1999, describe MOCVD of TiN thin films from TDMAT which are formed in a self-aligned manner, wherein the SiH4 treatment was stated to increase copper wettability and improve copper crystallization, while providing a barrier which did not significantly increase via resistance.
M. Eizenberg, in Chemical Vapor Deposition of TiN for ULSI Applications, Mat. Res. Soc. Symp. Proc. Vol. 427 1996, describes the use of TDMAT in CVD of TiN barrier layers.
A method of forming a titanium-based barrier metal layer includes preparing a substrate, including forming IC elements on the substrate; forming a titanium-based barrier metal precursor using a solution of about 5% by volume tetrakis (methylethylamino) titanium (TMEAT) and about 95% by volume octane; and depositing a titanium-based barrier layer on the substrate by MOCVD.
It is an object of the invention to provide a titanium-based barrier metal thin film layer precursor.
Another object of the invention is to provide a titanium-based barrier metal thin film layer precursor having a relatively high mean-time to failure.
Still another object of the invention is to provide a single-source precursor for a TiN barrier layer.
Yet another object of the invention is to provide a TiN precursor which negates the use of NH3 during the barrier layer deposition and fabrication.
A further object of the invention is to provide a titanium-based barrier metal thin film layer precursor having a relatively low leakage current.
Another object of the invention is to provide a precursor which is a mixture of TMEAT and octane.
A further object of the invention is to provide a TiN precursor which is relatively inexpensive and which provide good wetting characteristics for subsequent layer formation.
This summary and objectives of the invention are provided to enable quick comprehension of the nature of the invention. A more thorough understanding of the invention may be obtained by reference to the following detailed description of the preferred embodiment of the invention in connection with the drawings.